Weather is probably a major factor when you plan your trip to Ouro Preto, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and February, with an average temperature of 21°C, while the coldest months are July and August, with an average of 17°C. The rainiest months in Ouro Preto are December, January, November and February, with each month seeing an average of 259 mm of rainfall.